The invention relates to a closed flexible sachet in the form of an individual portion provided for extraction under pressure, containing at least one powdered substance for the preparation of a beverage chosen from ground roast coffee, tea, instant coffee, a mixture of instant coffee and ground coffee, a chocolate-type product or any other dehydrated edible substance, consisting of two identical flexible sheets or of a single folded flexible sheet of circular, oval or polygonal shape, creating a space for the powdered substance between the two sheets or between the two faces of the folded sheet, and the two sheets or the two faces of the folded sheet are welded over their periphery so that the sachet is substantially symmetrical with respect to its welding plane, the material used for the flexible sheets is impermeable to oxygen and to water vapor in order to preserve it, and the sachet is opened through the effect only of the rise in pressure which takes place upon injection of the extraction fluid.
Patent WO 94/01344 already relates to a closed flexible sachet provided for extraction under pressure. With this sachet, at the time of extraction, one of the flexible sheets is perforated so as to allow the arrival of the extraction water. The drawback of perforating the sheet is that firstly it is necessary to guarantee the seal over the entire periphery of the sachet and, secondly, if the coffee in the sachet is not compacted, it is not always guaranteed that the sachet will be perforated.
The present invention solves these problems by providing a closed sachet for extraction under pressure, in which it is unnecessary to guarantee the seal over the entire periphery of the sachet at the time of extraction and which makes it possible to avoid perforating one of the two flexible sheets.
The present invention thus relates to a closed flexible sachet in the form of an individual portion provided for extraction under pressure and in which the two flexible sheets or the two faces of the folded sheet extend over one side of the sachet beyond their welding line so as to provide, between the sheets or between the two faces of the folded sheet, a channel which allows the arrival of the extraction fluid, the channel being substantially perpendicular to the welding line on which it emerges.
The presence of the channel between the two flexible sheets or between the two faces of the folded sheet makes it possible to insert therein a needle or any other sharp element allowing the extraction water to be supplied without perforating or tearing one of the flexible sheets. It is unnecessary for the needle or the sharp element to enter into the channel: it is also possible to envisage the arrival of the extraction water precisely at the entry of the channel.
In one or other alternative, the sachet is not opened by inserting the needle or the sharp element to the extent of breaking the weld which closes the sachet, but it is the pressurized water which initiates and completely opens the weld of the sachet in order to allow the extraction liquid to enter. The water pressure is normally between 1 and 7 bar, i. e., in order to break the weld, a minimum pressure of water is required to open the weld.